CBSE Class 12-science Answered
The potential difference across a resistor 'r' carrying current 'I' IS Ir.
( 1 ) If the potential difference across 'r' is measured using a voltmeter of resistence 'Rv', s
how that the reading of voltmeter is less thsn the true value.
2. find the percentage error in measuring the potential differene by a voltmeter
3.At what value of Rv, does the voltmeter measures the true potential difference
Asked by Rajeev | 17 Feb, 2016, 10:55: AM
Expert Answer
Consider the above circuit.
Since the voltmeter has a resistance of Rv, suppose that the current I1 passes through it.
So, the current through resistor R is (I-I1).
Since the voltmeter is connected parallel to the resistor, the potential difference across the voltmeter is equal to the potential difference across the resistor R.
So applying ohm's law
I1Rv = (I-I1) R
IR = I1(R + Rv)
Substituting the values of I1 in (I-I1), we get,
The reading of voltmeter is less by.
Percentage error:
When , the error in potential difference . So the voltmeter will measure true potential difference.
Answered by Faiza Lambe | 22 Feb, 2016, 02:50: PM
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